In this chapter, we consider children's early language acquisition as it develops alongside three other core cognitive competencies: children's understanding of objects, children's understanding of the thoughts and feelings of others (i.e. their theory of mind), and children's knowledge of numbers and mathematical principles. We argue that while early language acquisition is initially supported by these three other competencies, the acquisition of words transforms them by providing a method for children to communicate and organise the information obtained through them. We do this by describing the key milestones occurring within each of the competencies and the genetic and environmental factors which place them at risk, with findings derived from a systematic review of cohort studies in English-speaking countries. A key message is that genetic and environmental circumstances are inextricably linked in predicting early cognitive development, and that some factors are reliably stronger in predicting poor outcomes than others. Additionally, there is clear evidence that income-related disparities are reliably measurable from the age of 3 and then steadily increase throughout the remainder of childhood.

Care injustice, sometimes termed the ‘postcode lottery’ arises when individuals cannot access services simply because of where they reside. The distribution and access to health and education services for children with language difficulties is explored in this chapter. There is a body of literature demonstrating that service availability and accessibility can differ markedly between metropolitan and rural settings. Here, we draw on available evidence to discuss the relationship between health inequities and inequalities, proposing a place-based approach as a potential solution, which encourages the location and distribution of services based on community need. This chapter also addresses the way in which many services have been historically developed, that is, along the traditional ‘clinical’ model rather than a model which considers and reviews the needs of a community from a population health perspective and likely needs of the child population. We conclude by highlighting some key steps that need to be taken to ensure the design and delivery of services to meet the future needs of the population, and outline some of the challenges in adopting this approach.

Language development in young children is clearly associated with the context in which children grow up. Of course, it has a strong biological developmental element but it is the interaction between the social and the developmental that is the focus of this book. Children’s language skills vary considerably at any one point in their development but especially over time. This chapter introduces the reader to some of the key concepts in the book and, in particular, focuses on how this interaction works for children with skills at the lower end of the language distribution, namely children with developmental language disorders, and how the patterns of these skills change over time. Key to understanding these issues is the need to follow large representative national samples of children for extended periods of time and assessing their performance at regular intervals, a feature of many chapters in the book. The book is targeted at academic, professional and an ‘informed’ public audience. The academic audience will include linguists, psychologists, speech and language pathologists, public health professionals and paediatricians and their equivalent in different countries. But it will also be important for health, education and public policy professionals.

Disparities in language development emerge in the first year of life and increase with age; consequently, infancy and toddlerhood are key periods whereby early language outcomes may be optimised via prevention and early intervention programs. As yet, the efficacy of programs promoting early language in the first three years of life remains unknown. This chapter provides the reader with findings from a systematic review of interventions aimed at improving child language outcomes for 0–3 year olds. Using a narrative synthesis, we examine and describe the evidence for effective language interventions across the preventive intervention spectrum (universal, selective, indicated/targeted). Specifically, we explore what works for who and under what circumstances. This review provides important insights about early language interventions, including factors contributing to positive outcomes. Findings also suggest how early interventions may be tailored to foster language outcomes for different groups of children (i.e. targeting children at-risk based on low socio-economic status or those with identified language difficulties). This review also highlights the need for further evaluation of promising interventions when applied to the broader population.

Although language development in children follows a predictable pattern and rate, it is common for interventions to be proposed to increase language skills especially when children are seen to be functioning behind their peers. The key argument is that environmental modifications have the potential to change language trajectories. These can be delivered at a universal level (for everyone) at a targeted-selected level (for groups perceived to be in need,) at a targeted-indicated level for those with an identified need, and at a specialist level (for those with the most pronounced difficulties). In this chapter we focus on two recent overviews of randomised controlled trials, one on parent–child book reading and a second on interventions delivered by professionals to promote language development. It focuses on the collective outcomes of these interventions rather than the details of the interventions themselves. The results suggest that, in the short term at least, there are reasonably consistent positive findings across a range of different interventions, although the effects vary considerably by outcome. It is not yet clear whether the downstream effects of such interventions are sustained or indeed whether children are able to catch up with their peers.